Beatrice Lang
The invention of electric traffic signals was driven by the need to control traffic, reduce accidents, and improve the flow of vehicles on roads. The earliest roads were chaotic, with pedestrians, bicycles, horses, carriages, and motor vehicles competing for right of way. The first non-electric gas-lit traffic lights were introduced in London in 1868 to manage horse-drawn traffic. Over time, the evolution of traffic signals led to the development of electric traffic signals. The first electric traffic signal was invented in 1912 by Lester Wire, a policeman in Salt Lake City, and installed in Cleveland, Ohio, in 1914. Since then, advancements in technology have improved the efficiency, reliability, and safety of traffic signals, with the introduction of computerized control systems, adaptive traffic signals, and energy-efficient LED lights.
| Characteristics | Values |
|---|---|
| Date of invention | 1868 (first traffic light), 1912 (first electric traffic light) |
| Inventor | John Peake Knight (J.P. Knight) (first traffic light), Lester Wire (first electric traffic light) |
| Location of first installation | London, near Westminster Bridge (first traffic light), Cleveland, Ohio (first electric traffic light) |
| Reason for invention | To control the flow of traffic, reduce accidents, and keep vehicles moving smoothly |
| Technology used | Gas-powered, human-operated with red and green lenses (first traffic light), electric with red and green lights and a buzzer (first electric traffic light) |
| Control | Manually controlled by a police officer (first traffic light), wired to a manually operated switch inside a control booth (first electric traffic light) |
| Impact | Reduced need for police officers to control traffic, improved road safety, and helped manage traffic congestion |
| Further developments | Addition of a third "caution" signal, staggered systems, computerized control systems, LED lights |
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What You'll Learn
The first electric traffic signal
The first electric traffic light was developed by Lester Wire, a policeman in Salt Lake City, Utah, in 1912. It was a two-colour signal with red and green lights and a buzzer, based on the design of James Hoge, to provide a warning for colour changes. The design allowed police and fire stations to control the signals in emergencies. The first electric traffic signal was installed by the American Traffic Signal Company, based on Hoge's design.
In 1916, Clevelanders John Tomko, CW Oppenlander, and SW Oppenlander invented an "electric semaphore" to "minimise traffic hazards". The device could be electronically controlled and had four arms for daytime use and twelve lights for night-time use. The first interconnected traffic signal system was installed in Salt Lake City in 1917, with six connected intersections controlled simultaneously from a manual switch.
In 1923, Garrett A. Morgan, an African American inventor who owned a sewing machine company in Cleveland, patented a traffic signal that revolutionized traffic control. Morgan invented a new type of traffic signal that used a T-shaped pole and, besides the “stop” and “go" signs, also had a "stop in all directions" sign to allow drivers and pedestrians to cross safely.
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The need for traffic control
In the early days, police officers controlled traffic, often in dangerous and congested conditions. The first traffic lights were introduced in London in December 1868 to reduce the need for police officers to direct traffic. These early gas-lit traffic lights were manually controlled by police constables using semaphore arms. However, they had some drawbacks, including a glare effect that made it difficult to see the signals during the day, and they sometimes exploded, posing a safety hazard.
As the use of automobiles grew, it became evident that more advanced traffic control systems were needed. The first electric traffic light was invented in 1912 by Lester Wire, a policeman in Salt Lake City, Utah. It was a two-colour system with red and green lights and a buzzer to provide a warning for colour changes. This system was installed in Cleveland, Ohio, in 1914, and it represented a significant step towards improving road safety and traffic flow.
Over the years, traffic signal technology has continued to evolve, with the introduction of interconnected systems, staggered systems, computerized control, and adaptive signals that can adjust based on traffic flow. These advancements have improved the efficiency and safety of traffic management, reduced congestion, and facilitated the movement of people to suburban areas. Today, modern traffic signal systems offer huge benefits at a lower cost compared to traditional road-widening methods to ease congestion.
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The drawbacks of previous methods
Secondly, the previous methods lacked adaptability and flexibility. Early traffic signals changed at set intervals, which was inefficient as not all streets experience the same traffic flow, leading to unnecessary waiting times for vehicles. This was a problem with the first electric traffic signals too, which had just two colours for stop and go, and lacked a caution signal.
Thirdly, the early methods of traffic control lacked the sophistication and safety features of modern electric traffic signals. For example, the early tower signals were frequently struck by vehicles, and the glare effect from the sun on the coloured lens of early traffic lights made it impossible to identify the correct signal at times.
Finally, the older methods of traffic control were not able to prioritize certain vehicles or adapt to changing traffic conditions in real-time. This led to longer waiting times and increased congestion, especially during periods of high traffic. The introduction of electric traffic signals, with their ability to be interconnected and controlled remotely, revolutionized the handling of traffic in congested city streets.
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The evolution of traffic signals
In 1912, the first two-lens (red/green) electric traffic light system was invented by Lester Farnsworth Wire, a policeman in Salt Lake City, Utah. This design resembled a four-sided birdhouse mounted on a tall pole, and while Wire did not patent his invention, it marked a significant step towards modern electric traffic signals. The following year, in 1913, James Hoge created the first electric traffic signal, which used illuminated "stop" and "move" signs instead of coloured lights. Hoge's design was further developed, and on August 5, 1914, the first electric traffic lights were installed in Cleveland, Ohio, at the intersection of East 105th Street and Euclid Avenue.
The early electric traffic signals faced challenges, including the need for manual operation and the glare effect caused by the sun shining on the coloured lenses. To address these issues, improvements were made over the years, such as equipping traffic lights with visors to reduce glare and connecting them to manual switches inside control booths to prevent conflicting signals. The introduction of interconnected traffic signal systems, such as the one installed in Salt Lake City in 1917, allowed for better control and coordination of traffic flow.
The 1920s saw significant advancements in traffic signal technology, with inventors like Garrett Morgan and Charles Adler Jr. making notable contributions. Morgan, after witnessing a severe accident, patented a T-shaped traffic signal in 1923 that included a "caution" signal, allowing drivers and pedestrians to cross safely. Adler introduced the concept of sonic activation, where drivers could change a red light by honking their horns, and he also invented the first pedestrian push button signal in 1929.
The 1960s brought about a new era of adaptive traffic signals, which could adjust based on traffic flow. This decade also witnessed the widespread computerization of traffic lights, improving traffic flow, efficiency, and safety. The introduction of new lighting sources using discharge tubes addressed the glare issue, reduced energy consumption, and lengthened the lifetime of the lights. The end of the 1980s marked another milestone with the introduction of Light Emitting Diode (LED) lights, further reducing energy consumption and extending the replacement cycle.
Today, modern traffic signal systems have become even smarter, with the ability to adapt to traffic and prioritize certain vehicles, such as emergency services. The integration of connected vehicles and AI-driven traffic control is expected to bring further changes to the system, potentially introducing new colours and improving efficiency at intersections. The evolution of traffic signals continues to be driven by the need to enhance road safety, ease congestion, and improve the overall commuting experience for drivers and pedestrians alike.
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The future of traffic signals
The electric traffic signal was invented to alleviate the chaotic experience of navigating America's roads, where pedestrians, bicycles, horses, streetcars, and motor vehicles all competed for right of way. The first electric traffic signal was put in place in 1914, and since then, traffic light technology has advanced significantly.
Smart traffic signals also have preemptive capabilities, such as Emergency Vehicle Preemption (EVP) systems, which give priority to first responders rushing to a scene. These systems use predictive traffic light algorithms that reduce costly delays and dangerous accidents.
The integration of digital control systems and the Internet of Things (IoT) has revolutionized traffic signal operation. IoT-enabled signals adjust timings dynamically based on live traffic data, and data analytics inform future traffic planning and real-time adjustments.
Artificial Intelligence (AI) algorithms optimize signal timing by analyzing historical and real-time data. Vehicle-to-Infrastructure (V2I) Communication allows smart signals to communicate with connected vehicles, providing real-time updates and improving traffic flow.
Modern traffic signals offer significant benefits across economic, environmental, and safety domains. These include lower energy costs, reduced maintenance expenses, improved traffic flow, enhanced urban appeal, reduced carbon emissions, and minimized light pollution.
Strategic innovations and digital and sustainable transportation solutions contribute to the transformation of urban landscapes, enhancing safety and supporting a sustainable, low-carbon future.
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Frequently asked questions
The history of traffic lights is associated with the growth of the automobile. With the increase in automobiles, there was a need for more efficient and organized ways of controlling traffic.
The first electric traffic signal was invented in 1912 by Salt Lake City, Utah police officer Lester Wire. However, it is widely regarded that the first electric traffic signal was installed in Cleveland, Ohio, on August 5, 1914.
The first electric traffic signals had two colours, red and green, with the words "stop" and "move". They were designed to look like a 4-way birdhouse mounted on a tall pole with red and green bulbs inside.
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